New Horizons is healthy and continuing to speed outward across the Kuiper Belt. Our spacecraft is 61 times as far from the Sun as Earth, or over 5.5 billion miles from home! Radio signals, traveling to and from New Horizons at the speed of light - about 186,000 miles per second - take about nine hours to cover that distance.
New Horizons is about halfway through a hibernation period that by Alan Stern | PI New Horizons
Boulder CO (SPX) Feb 18, 2025
New Horizons is healthy and continuing to speed outward across the Kuiper Belt. Our spacecraft is 61 times as far from the Sun as Earth, or over 5.5 billion miles from home! Radio signals, traveling to and from New Horizons at the speed of light -- about 186,000 miles per second -- take about nine hours to cover that distance.
New Horizons is about halfway through a hibernation period that began Oct. 2 and will end on April 3. Even while in hibernation, the spacecraft still collects science data around the clock from three of our seven onboard instruments, measuring the dust and radiation environment of this distant part of our Sun's heliosphere.
Although the spacecraft is hibernating, our team isn't. We're already planning activities for an active period from April to August, as well as working on upgrades of our onboard fault-protection and on-the-ground mission control software. In addition, the team is poring over data we collected at the Japanese Subaru Telescope last year to identify new Kuiper Belt objects (KBOs) for New Horizons to study, archiving data to be deposited in NASA's Planetary Data System, and publishing new results.
Some examples of current and upcoming research papers from the New Horizons team include:
+ The most precise measurements ever made of the universe's cosmic optical background.
+ The first all-sky map of the hydrogen (the most common element in space) distribution in nearby interstellar space, taken from a vantage point beyond the obscuring hydrogen fog of the inner solar system.
+ The first all-sky map of the universe's cosmic ultraviolet background, also made without various kinds of inner solar system obscuration that hindered previous such maps.
+ An exploration of what might be behind the unexpectedly high dust-impact rates New Horizons is detecting in the distant reaches of the Kuiper Belt.
+ A new and improved shape calculation for KBO Arrokoth, which New Horizons reconnoitered in 2019, that puts new constraints on how Arrokoth and similar KBOs were formed.
+ A study of the heliosphere's so-called pickup ions, which provide much of the pressure exerted where New Horizons is traversing the distant reaches of the Sun's heliosphere.
+ The first observations of Uranus' far side since Voyager studied the ice giant in the 1980s, revealing new details about how Uranus' atmosphere works.
Discoveries of almost 250 distant KBOs.
A study of strange, "contrast reversal" features on Pluto's surface that switch from dark to light, depending on viewing angle.Back to our work on the new spacecraft fault protection software and new mission control software: the former will enable New Horizons to operate safely as its nuclear battery declines in power. The new mission control software will modernize our ground systems, ensuring their reliability over the long term.
We're also planning a detailed campaign to study the Sun's so-called termination shock, which is where the solar wind in the Sun's outer heliosphere slows down to subsonic speeds as it interfaces with the Milky Way galaxy's own gas (the so-called "interstellar medium"). To date, the only spacecraft to explore the termination shock are Voyagers 1 and 2, which crossed this region long ago. Fortunately, New Horizons carries more modern and more capable instruments that can improve on the many termination shock discoveries that the two Voyagers made.
Four of the instruments aboard New Horizons will be searching for and exploring the termination shock in the years to come, and delivering the first new gas, radiation, dust and charged particle data on the region since Voyager. What will New Horizons find? We don't entirely know, but we do know that no other spacecraft is going to be crossing the termination shock for decades to come -- so whatever New Horizons finds will have lasting scientific value.
I also want to point out a new capability that we hope to use (soon) to look for new KBOs for New Horizons to study and, possibly, even fly by. The Vera Rubin Observatory (VRO) is a National Science Foundation facility coming online this year with capabilities to track faint moving targets -- like KBOs -- and conduct many other kinds of planetary science and astrophysics investigations. You can read more about VRO here, and stay tuned for more on our plans for using VRO in future PI Perspectives.
Finally, I want to recognize and thank our long-term project manager, Helene Winters of the Johns Hopkins Applied Physics Laboratory (APL), who is stepping aside after nearly nine years of leadership on New Horizons. Helene deserves a lot more credit for our successes than most people know, and we will miss her. Helene's successor will be APL's Caitlin Shearer, who comes to us after experience on several recent space missions, perhaps most notably on NASA's DART asteroid impactor planetary defense mission.
As I close on this first mission update of 2025, I want to remind you that we've updated our mission website at http://pluto.jhuapl.edu/ to include new details about our extended mission into the Kuiper Belt and the Sun's outer heliosphere- so check that out when you get a chance.
And that's my update for now. I'll write again once New Horizons is out of hibernation this spring. In the meantime, I hope you'll always keep exploring - just as we do!
Alan Stern is the New Horizons Mission Principal Investigator | Southwest Research Institute
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